Where I tell people they have no game

Updated RSPM Formula

After reviewing the original RSPM formula, I’ve decided to tweak it a little bit. The reason was that the original RSPM formula was based on a straight linear regression between box-score stats and RAPM, and the result was that it was better to be a bad free throw shooter than to be a good free throw shooter. That might seem counter-intuitive, but believe it or not, there’s a negative correlation between free throw accuracy and RAPM. I attribute this to players such as Shaquille O’Neal, Ben Wallace, Dwight Howard and others producing outstanding RAPM ratings despite their poor free throw shooting.

I have fixed this glitch by simply removing free throw makes from the regression analysis. Here is the new formula:

I really like this formula because it doesn’t reward players for high-volume, low-efficiency shooting. Let’s say a player’s per-36 minute averages are 8 field goal makes, 20 field goal attempts, and 16 points. Those averages would actually hurt a player’s RSPM by -3.1 points.

As I mentioned before, this formula is based on box-score statistics and as a result will struggle to accurately measure either defense or the “hidden aspects” of basketball.

Examples of players the formula will struggle with: Luol Deng, Tony Allen, Nick Collison, Shane Battier, and even Kevin Garnett. That’s because these are all players who play great individual defense and are fantastic team players.

But I do think RSPM is a pretty good estimate for the vast majority of NBA players out there. I’ll keep researching and seeing if any more tweaks would be a good idea.